The west London borough wanted to reduce its target from 65 per cent to just 40 per cent, which would leave many of the area's poorest residents living in low-quality temporary accommodation.
He said: 'Hammersmith and Fulham used to be one of London's leading boroughs for the provision of affordable housing. Not only did they have a high target of 65 per cent, but they were actually delivering well over that target. Now the council is proposing a giant leap backwards.'
The plans were kicked into touch because the Conservative-run council's new target did not conform to Livingstone's London Plan, which calls for 50 per cent of all new homes in London to be affordable.
Any proposals that do not conform to the Mayor's plan have to be revised or will be rejected by central government.
Livingstone added: 'The cuts they propose in new affordable homes for local people are unacceptable and contrary to my statutory London Plan.
'I am determined they should be made to face up to their responsibilities and at the least meet my target that half of all new homes should be affordable.'